The present invention relates generally to the production of reinforced flexible hose having a knitted pattern of yarn or other fabric material secured upon the exterior hose surface, and more particularly to an improved system and associated method for the positive feeding of the yarn in multiple strands around the hose at a controlled and synchronized rate using a single motor drive and novel feeder head assembly that enhances the product quality and efficiency of production of the reinforced hose.
Flexible hose made of rubber, synthetic plastics, and the like have limited burst strength so that their use in industry for the transmission of fluids at high pressure require a reinforcement of their exterior surface. A longstanding and well known method for reinforcing such flexible hose uses a circular knitting machine that applies the yarn or like fabric material in a mesh like pattern around and along the exterior of the hose as it is drawn through the knitting machine. A common type of circular knitting machine generally adapted for use in hose reinforcement comprises a hollow cylindrical member, called a knitter head, containing a plurality of latch needles that are symmetrically arranged about the knitter head and made to reciprocate within equally spaced guide slots axially formed along the head, the reciprocating action of the needles being imparted typically by one or more cam members that are mounted for rotation along with the knitter head. Individual strands of yarn, usually drawn from separate cones or spools mounted on the knitter machine, are directed in a path to each latch needle in the knitter head so that the reciprocating needle will engage the strand in the one direction and pull the yarn through the knitter head and onto the hose exterior in the opposite direction as the hose travels therethrough. This process is repeated with all the reciprocating needles acting together around the knitter head to produce a stitched pattern of the knitted yarn surrounding the hose that can be varied in size and disposition of the stitches to provide it with the required reinforcement strength.
In the past, such circular knitting machines would rely on the tension adjustment of the yarn as it was drawn through the knitter head, typically using a spring-loaded washer device, to regulate the flow rates of the yarn strands and thereby control the stitching pattern of the reinforcement. This process of tension adjustment, however, was often inconsistent and generally proved unreliable, with resulting variations in yarn tension that caused uneven patterns of reinforcement along the hose product, the uneven removal of yarn from the individual spools, and a damaging stress on the knitting needles that would in turn result in needle failure and machine breakdown. Supplemental positive feeding devices, such as that described in U.S. Pat. No. 5,309,738, have been devised to overcome the problems of strand tensioning and the detrimental effects that result when knitter needles alone are used to draw the yarn strands from their respective supply packages and through the knitter head. These and other positive yarn feeding devices have been satisfactory and effective in equalizing the feed rates of the individual yarn strands onto the knitter head and in coordinating those feed rates with the rate at which the knitter head with its reciprocating needles acts upon the respective strands to knit the desired reinforcement pattern about the hose. Although existing positive yarn feeding devices have been effective in their operational performance, they have generally required the use of multiple drive motors with associated mechanical and electrical means to maintain them in unison so that the final reinforced hose product is made to the desired specifications. Thus, while generally found to be effective, the multi-drive positive feeding systems of the prior art have been relatively expensive to assemble and run and, because of the essential coordination required between the separate drives, they are inherently at risk to a possible system failure or disorientation between drives that can result in costly downtime of the hose reinforcement system as well as the production of defective quantities of hose product having inadequate or improper reinforcement. A need therefore exists for an improved system and associated method for positive yarn feeding to be incorporated within a circular knitting machine used to produce reinforced flexible hose.
Accordingly, it is a general purpose and object of the present invention to provide an improved positive yarn feeding device and associated method for use in the production of reinforced flexible hose.
A more particular object of the present invention is to provide a positive yarn feeding system that delivers multiple strands of yarn to the knitter head of a conventional circular knitting machine at a controlled and synchronized rate and in a manner more economical and efficient than heretofore devised.
Another object of the present invention is to provide an improved positive yarn feeding system for use in the production of reinforced flexible hose that is reliable in its operation so as to reduce downtimes and defects in the production process.
Still another object of the present invention is to provide an improved positive yarn feeding system for knitted reinforcement of flexible hose that enhances the quality of the reinforced hose product and affords greater control of the knitted pattern applied during production.
A still further object of the present invention is to provide a positive yarn feeding system that is easily assembled and readily adapted to the knitter heads of conventional circular knitting machines used for flexible hose reinforcement.
Briefly, these and other objects of the present invention are accomplished by an improved system and associated method for the positive feeding of multiple strands of yarn from spools using a single motor drive within a hose reinforcement knitting machine of the type having a central knitter head with reciprocating needles that stitch a reinforcement web pattern around flexible hose moving through the central axis of the machine. The positive yarn feeding system comprises a feeder head assembly attached to rotating framework of the knitting machine coaxially with the knitter head. The feeder head assembly includes a circular support plate having an axial opening and a plurality of positive feeder units, one for each of the yarn strands intended for knitting. The feeder units are arranged in a radial pattern about the periphery of the support plate and interconnected for concurrent rotation by a coupling belt extended about upper wheels on the units. The feeder head assembly further includes a central gear mounted in a stationary position atop the support plate, a planetary gear rotatably mounted upon the support plate in position to engage the central gear, an adjustable control gear secured atop the planetary gear, and a drive belt engaged about the control gear and a proximate one of the feeder units to provide the rotational drive for all. As the single motor drive rotates the framework of the knitter machine and its mounted spools, the feeder head assembly rotates in unison and by means of the combined arrangement of interconnected gears assembled thereto, synchronizes the drawing of the yarn strands through the feeder units and into the central knitter head.
For a better understanding of these and other aspects of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings in which like reference numerals and characters designate like parts throughout the figures thereof.